1. Field of the Invention
The present invention relates to an image display device; and, more particularly, to a sharpness enhancing apparatus and method of an image display device.
2. Description of Related Art
Generally, digital image display devices such as liquid crystal display (LCD) or organic light emitting diode (OLED) display image signals such as television broadcast signals inputted from the outside, signals inputted from a video card, or the like. Furthermore, digital image display devices can display signals received through various external input devices such as a digital versatile disk (DVD) player, a set-top box, or the like.
Such image display devices include a video signal processor that converts an external signal into a certain format suitable for displaying the signal. The video signal processor includes a scaler that adjusts an appropriate resolution to make an input signal suitable for a display device, converts the input signal into an RGB or YCbCr signal, and converts an input signal format into a final output format. In addition, the video signal processor enhances the contrast of an image signal and determines the sharpness of an image signal.
Regarding the image signal outputted to the image display device, sharpness is an important factor in displaying an image at a satisfactory level. This is because users prefer display devices that can display high-quality images clearly without noise. Therefore, displaying images with good sharpness is the first consideration. Sharpness is also construed as definition in scholastic terms, and represents clearness at boundaries between dark and bright portions of the image.
However, conventional sharpness enhancing methods, which have been known until now, batch-process the whole image. In such methods, enhancement degrees may be different according to image characteristics. Image characteristics may be different depending on positions in a total image. Thus, if the sharpness enhancing methods are applied indiscriminately without considerations of the image characteristics, noise may be generated because sharpness enhancement degrees are different according to the image characteristics.